Abstract

We report the demonstration of a pulsed atomic lead (Pb) vapor-based vacuum
ultraviolet frequency converter from 233 to 186 nm with unity
photon-conversion efficiency. This conversion is attained without phase matching.

Figures (3)

Schematic
diagram of the experimental setup and energy-level diagram for atomic Pb.
Level assignments: |1〉, 6p2P30 (ground); |2〉, 6p2P32; |3〉, 6p7sP31; and |4〉, 6p9sP31. Hyperfine structure is not shown. The probe laser at 283 nm
and coupling laser at 406 nm have opposite circular polarizations
and prepare a large atomic coherence; the mixing field at 233 nm
has the same-sense circular polarization as the coupling laser and mixes with
the coherence to generate a sum frequency at 186 nm. BC1, BC2,
beam combiners.

Photon-conversion
efficiency from the applied 233-nm mixing beam to the generated
186-nm beam as a function of the detuning Δω from the upper 6p9sP31 level. Inset: calculated conversion efficiency. The Pb metal density–length
product for these data is 1.5×1017atoms/cm2.

Saturation
behavior and depletion in the 186-nm FWM process at a detuning of 40cm-1 below the 6p9sP31 resonance. The generated 186-nm energy increases
linearly with the applied 233-nm energy, indicating constant small-signal
conversion efficiency (≈70%, as indicated by the solid line) and then saturates. Inset: recorded
waveforms showing depletion of the 233-nm mixing field.
(a) 233-nm mixing field at the exit of the heat pipe when the probe and the
coupling lasers are blocked (no conversion). When significant generation occurs,
the 233-nm field at the exit is depleted (b), and the 186-nm
beam is generated (c). Trace (c) has been normalized and shifted from the
other curves for better perspective.